An ultrasonic testing method has been employed widely as a nondestructive inspection method for a pipe such as a steel pipe. In the ultrasonic testing method, a coupling medium such as water is interposed between the pipe and an ultrasonic probe, ultrasonic waves transmitted from the ultrasonic probe are applied to the pipe, and the ultrasonic waves reflected by the pipe are received by the ultrasonic probe.
As an ultrasonic testing method in which ultrasonic probe is disposed under a pipe laid in the horizontal direction, there is a publicly known method for ultrasonic testing of a pipe P in which, as shown in FIG. 1, while an ultrasonic probe 1 is immersed in water W stored in a water tank T, the lower surface of the pipe P is immersed partially in the water W, and the pipe P is conveyed in the axial direction thereof and is rotated in the circumferential direction thereof (for example, refer to “Ultrasonic Testing Series (III) Ultrasonic Testing Method for Seamless Steel Pipe” from the Iron and Steel Institute of Japan, Apr. 15, 1988, pp. 95-96).
According to the above-described method, since the water W serving as a coupling medium can be interposed stably between the pipe P and the ultrasonic probe 1, accurate ultrasonic testing can be performed.
In the configuration shown in FIG. 1, unfortunately, the pipe P is supported at least at two points outside the water tank T. The problem, therefore, is that ultrasonic testing cannot be performed on a pipe end portion, where such a two-point support cannot be used, within the water W in the water tank T. Therefore, the configuration shown in FIG. 1 is mainly used in ultrasonic testing of the central portion of pipe except the pipe end portions.
On the other hand, as an ultrasonic testing apparatus for a pipe end portion, there is a publicly known apparatus provided with an ultrasonic probe and a follow-up device, which causes the ultrasonic probe to follow the pipe rotating in the circumferential direction (for example, refer to JP2008-139191A).
In the case where the ultrasonic probe for ultrasonic testing of the pipe end portion is disposed over the pipe laid in the horizontal direction, it is conceivable for example to use a structure that causes coupling medium to flow down between the ultrasonic probe and the pipe end portion. However, the same structure cannot be used in the case where the ultrasonic probe is disposed under the pipe. In the case where the ultrasonic probe for ultrasonic testing of the pipe end portion is disposed under the pipe, it is conceivable for example to use the water tank as shown in FIG. 1 and immerse the support structure and the follow-up device for the pipe into water in the water tank in a certain configuration. Unfortunately, such a configuration may not be practical because it may be complicated and require a strong waterproof structure, which leads to poor maintainability and an increased cost.